1. Field of the Invention
The present invention relates generally to power converters, and more particularly, to a switching circuit for a primary-side regulated resonant power converter.
2. Description of the Related Art
Recently, most prior-art technologies are developed on flyback switching topology, such as “Switching Control Circuit for Primary-side Controlled Power Converters” U.S. Pat. No. 7,362,592, and “Primary-side Controlled Switching Regulator” U.S. Pat. No. 7,352,595, etc.
In resonant switching power converters, the inherent soft-switching characteristic thereof is advantageous to reduce the EMI (Electro-Magnetic Interference). However, in conventional arts, a secondary feedback circuit is still required for providing the information of an output voltage of the resonant power converter. The device counts of the secondary feedback circuit dominate the main cost and lower the conversion efficiency of the resonant power converter.
As a result, there is a need to provide a primary-side regulated resonant power converter with lower cost and higher power conversion efficiency.